Plastic axial flow fan blade for air conditioner

Abstract

The utility model relates to the field of air conditioner heat dissipation systems, in particular to a plastic axial flow fan blade for an air conditioner, which comprises a hub and a plurality of blades, and the inner edges of the plurality of blades are integrally connected to the outer side wall surface of the hub and are regularly arranged along the circumferential direction. Each blade comprises a blade body integrally formed with the hub and a movable blade connected to the blade body in a buckled mode. A groove is formed in the leeside of the blade body, the movable blade is fixedly connected to the groove in a clamped mode, and the edge of the movable blade is connected with the edge of the groove of the blade body. The blade body and the movable blade jointly form a hollow two-half structure, and criss-cross reinforcing ribs are arranged in the hollow two-half structure. The scheme has the advantages that the structural strength is improved, the forming defects are reduced, the weight is reduced, and the aerodynamic performance is optimized.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning heat dissipation systems, and in particular to a plastic axial flow fan blade for air conditioning. Background Technology

[0002] As a key component of the heat dissipation system of an air conditioner outdoor unit, the plastic axial fan blades used in air conditioners directly affect the overall operating efficiency and reliability of the unit due to their structural strength and dimensional stability. Axial fan blades manufactured using traditional injection molding processes typically adopt a solid, integral structure, with a larger wall thickness at the blade root and hub connection area to meet structural strength requirements, and the blade thickness gradually decreasing from the root to the tip.

[0003] However, this traditional design has significant drawbacks. First, the thick-walled structure leads to severe molding defects. The thick-walled design in the blade root region results in non-uniform cooling during injection molding. The outer layer material solidifies rapidly upon contact with the mold surface, while the core melt continuously shrinks, generating internal tensile stress and causing a warpage deformation of 0.8%-1.2%. This deformation not only compromises the aerodynamic profile accuracy of the blade, with surface deviations reaching ±0.5mm, but also leads to dynamic imbalance errors, causing a vibration amplitude increase of 3-5μm. These problems severely affect the performance and service life of the wind turbine blades.

[0004] Secondly, porosity significantly weakens the mechanical properties of the fan blades. In conventional solid blades, the melt flow path in the thick-walled region is excessively long, typically exceeding 50mm. This causes the melt temperature to drop at the front end of the injection molding process at a rate 23%-28% faster than in the thin-walled region, creating a flow stagnation effect. This prevents trapped gas from effectively escaping, resulting in diffuse pores with a diameter of 0.1-0.3mm. When the porosity exceeds 2.5%, tensile strength decreases by 18%-22%, and fatigue life is reduced to less than 60% of the standard value. This reduction in mechanical properties directly affects the reliability and service life of the fan blades.

[0005] Furthermore, traditional solid, one-piece structures suffer from low material utilization and high weight. Excessive material usage not only increases production costs but also adds to the weight of the fan blades, thus affecting the overall energy efficiency of the air conditioning system. Simultaneously, due to structural limitations, traditional fan blades also face bottlenecks in aerodynamic performance optimization, making it difficult to further improve the heat dissipation efficiency of the air conditioning system.

[0006] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0007] In order to solve the above problems, the purpose of this utility model is to provide a plastic axial flow fan blade for air conditioning, which has the advantages of improving structural strength, reducing molding defects, reducing weight, and optimizing aerodynamic performance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This application provides a plastic axial flow fan blade for air conditioning, with the following technical solution: It includes a hub and multiple blades, the inner edges of which are integrally connected to the outer wall of the hub and arranged regularly along the circumference. Each blade includes a blade body integrally formed with the hub, and movable blades snapped onto the blade body. A groove is formed on the leeward side of the blade body, and the movable blades are snapped and fixed into the groove, with the edge of the movable blades connecting to the edge of the groove in the blade body. The blade body and the movable blades together form a hollow two-half structure, and the interior of the hollow two-half structure is provided with crisscrossing reinforcing ribs.

[0010] Furthermore, this application also proposes that the buckle structure includes an elastic hook disposed on the movable blade and a slot disposed on the edge of the groove, wherein the elastic hook achieves locking by deforming and embedding into the slot.

[0011] Furthermore, this application also proposes that the groove is located on the leeward side of the blade near the leading edge of the blade, and the width of the groove along the direction from the leading edge to the trailing edge of the blade accounts for 60% to 90% of the total width of the blade.

[0012] Furthermore, this application also proposes that a reinforcing rib is provided in the groove, and when the movable blade is engaged and fixed in the groove, the reinforcing rib supports the inner end face of the movable blade.

[0013] Furthermore, this application also proposes that the reinforcing ribs include transverse reinforcing ribs and longitudinal reinforcing ribs, wherein the transverse reinforcing ribs and longitudinal reinforcing ribs intersect to form a grid-like structure, and a grid-like cavity is formed between adjacent reinforcing ribs.

[0014] Furthermore, this application also proposes that the transverse reinforcing ribs have an arc-shaped structure extending from the leading edge of the blade to the trailing edge of the blade, and the longitudinal reinforcing ribs have an arc-shaped structure extending from the inner edge of the blade to the outer edge of the blade.

[0015] Furthermore, this application also proposes that the thickness difference of the blade body from the inner edge to the outer edge of the blade in the radial direction be controlled within 5%.

[0016] Furthermore, this application also proposes that the thickness of the reinforcing rib is 1 / 3 to 1 / 2 of the wall thickness of the hollow two-half structure.

[0017] Furthermore, this application also proposes that the hub and blade body are made of high-strength engineering plastic and are integrally formed by injection molding.

[0018] As described above, the plastic axial flow fan blade for air conditioning provided in this application includes a hub and multiple blades. Each blade comprises a blade body integrally formed with the hub and movable blades connected by snap-fit ​​mechanisms, together forming a hollow two-part structure with crisscrossing reinforcing ribs inside. This design reduces material usage and weight through the hollow structure, improves structural strength through the reinforcing ribs, and reduces molding defects through the split design. It also optimizes aerodynamic performance. Therefore, the plastic axial flow fan blade for air conditioning provided in this application has the advantages of improved structural strength, reduced molding defects, reduced weight, and optimized aerodynamic performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the end face of a plastic axial flow fan blade for air conditioning provided in this application.

[0020] Figure 2 for Figure 1 AA sectional view.

[0021] Figure 3 This is a schematic diagram of the assembly of the blade body 3 and the movable blade 4. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection or an electrical connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0026] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] like Figures 1-3 As shown, this embodiment relates to a plastic axial flow fan blade for air conditioning, including a hub 1 and multiple blades 2. The inner edges of the blades 2 are integrally connected to the outer wall of the hub 1 and arranged regularly along the circumference. Each blade 2 includes a blade body 3 integrally formed with the hub 1, and movable blades 4 snapped onto the blade body 3. A groove 5 is formed on the leeward side of the blade body 3, and the movable blades 4 are snapped and fixed onto the groove 5, with the edge of the movable blades 4 connecting to the edge of the groove 5 of the blade body 3. The blade body 3 and the movable blades 4 together form a hollow two-half structure, with crisscrossing reinforcing ribs inside the hollow two-half structure. This technical solution decomposes the traditional integral thick-walled structure into two relatively thin-walled components through a split design, where the blade body 3 and the movable blades 4 are reliably connected through a precisely fitted snap-fit ​​structure. The hollow structure design effectively reduces material accumulation, improving wall thickness uniformity to over 95%, thereby reducing temperature gradient differences during injection molding. The optimized arrangement of the internal reinforcing rib mesh provides sufficient structural rigidity while reducing weight. Specifically, the mesh-like reinforcing ribs decompose stress concentration areas into multiple small units, reducing the maximum equivalent stress by 35%-45%. Grooves 5 are constructed on the leeward side of the blade body 3 to ensure that the windward side of the blade body 3 is integral. The connection edge between the movable blade 4 and the blade body 3 adopts a transition curved surface design to ensure aerodynamic profile continuity, with surface roughness controlled below Ra3.2. This structural design keeps the molding shrinkage rate difference within 0.15%, effectively solving the warping deformation and porosity defects caused by the thick-walled structure of traditional solid blades.

[0028] In a specific implementation, the snap-fit ​​connection can employ a structure where an elastic hook 7 and a slot engage. Specifically, the snap-fit ​​structure includes an elastic hook 7 mounted on the movable blade 4 and a slot located at the edge of the groove 5. The elastic hook 7 achieves locking by deforming and embedding itself into the slot. As a preferred embodiment, the elastic hook 7 can be designed as an inverted conical structure, with the thickness of its free end achieving reliable engagement through elastic deformation. Furthermore, a guide slope can be provided at the edge of the groove 5 to facilitate alignment during assembly of the movable blade 4. As a preferred embodiment, 3-5 elastic hooks 7 are arranged at equal intervals along the length of the movable blade 4, with the spacing between adjacent hooks being 15%-25% of the blade width. This technical solution complements the deformation capability of the elastic hook 7 with the rigid constraint of the slot. During assembly, the elastic hook 7 undergoes controllable elastic deformation to achieve smooth embedding, and after recovering its deformation, it forms a three-point contact interference fit with the slot.

[0029] like Figure 1 As shown, groove 5 is located on the leeward side of the blade near the leading edge, and the width of groove 5 along the direction from the leading edge to the trailing edge accounts for 60% to 90% of the total blade width. This technical solution, by precisely defining the position and width ratio of groove 5, ensures that the connection area avoids high aerodynamic load zones while ensuring that the effective connection area between the movable blade 4 and the main body reaches 45%-65% of the blade's projected area. Experimental data shows that this design reduces the stress concentration factor in the connection area from 2.8 in the traditional structure to below 1.5, and controls the blade leading edge profile accuracy deviation within ±0.15mm. Compared with integral solid blades, the hollow structure combined with the optimized groove 5 parameters reduces the blade weight by 18%-22% while increasing the first-order natural frequency by 12%-15%, effectively solving the forming defects and aerodynamic performance degradation problems caused by thick-walled structures.

[0030] In such Figure 1 and 3In the specific implementation shown, a reinforcing rib is provided in the groove 5. When the movable blade 4 is snapped into the groove 5, the reinforcing rib supports the inner end face of the movable blade 4. This technical solution effectively improves the bending stiffness and load-bearing capacity of the connection area by directly supporting the inner end face of the movable blade 4 with the reinforcing rib. The reinforcing rib disperses the aerodynamic load borne by the movable blade 4 to the blade body 3, avoiding stress concentration at the snap-fit ​​connection. Compared with the existing integral solid blade, this structure solves the problem of insufficient structural strength in the connection area while maintaining the advantages of hollow and lightweight design. Specifically, the reinforcing rib support increases the bending stiffness of the connection interface by about 40% and reduces local deformation by more than 60%. The grid-like reinforcing rib structure can reduce the stress concentration factor from 3.5 to below 1.8. Therefore, with the same amount of material, this design enables the wind turbine blade to maintain better dimensional stability at high speeds and significantly reduces the risk of connection failure. As a preferred implementation, the thickness of the reinforcing rib can be set to 1 / 3 to 1 / 2 of the wall thickness of the hollow structure, and the spacing between adjacent reinforcing ribs is controlled within the range of 10-15 mm. For example, the reinforcing rib can be made of the same engineering plastic material as the blade body 3, and integrally molded with the groove 5 through injection molding. Furthermore, an interference fit of 0.1-0.3mm can be provided at the top of the reinforcing rib to ensure close contact with the inner end face of the movable blade 4.

[0031] The stiffeners include transverse stiffeners 9 and longitudinal stiffeners 10. The transverse stiffeners 9 and longitudinal stiffeners 10 intersect to form a grid-like structure, and grid-like cavities 11 are formed between adjacent stiffeners. The stiffeners can be arranged transversely, longitudinally, or in a grid-like intersecting arrangement. In a specific embodiment, the transverse stiffeners 9 can extend along the leading edge to the trailing edge of the blade, and the longitudinal stiffeners 10 can extend along the inner edge to the outer edge of the blade. The transverse stiffeners 9 can extend in a straight line or arc along the leading edge to the trailing edge of the blade, and the longitudinal stiffeners 10 can extend in a straight line or arc along the inner edge to the outer edge of the blade. As a preferred embodiment, the intersection angle between the transverse stiffeners 9 and the longitudinal stiffeners 10 is 70° to 110°. The shape of the grid-like cavities 11 can be rectangular, rhomboid, or hexagonal, and the cavity area accounts for 40% to 60% of the total area of ​​a single grid unit. The cross-sectional shape of the stiffeners can be rectangular, trapezoidal, or I-shaped, wherein the I-shaped cross-section can increase the bending section modulus by 15% to 20% with the same material usage. Furthermore, the arc-shaped structure of the transverse stiffener 9 can be specifically designed as a continuous curve consistent with the airflow direction from the leading edge to the trailing edge of the blade, with the radius of curvature optimized and matched according to the blade profile. As a preferred embodiment, the cross-sectional shape of the arc-shaped stiffener 9 can be trapezoidal or semi-circular, wherein the angle of the inclined sidewall of the trapezoidal cross-section is controlled within the range of 45°-60° to balance the demolding performance and structural load-bearing efficiency during injection molding. The arc-shaped direction of the longitudinal stiffener 10 coincides with the radial load transmission path of the blade, and in specific implementation, it can be designed as an involute or parabolic distribution, with the spacing between each longitudinal stiffener 10 being gradient-adjusted along the radial direction according to the principle of equal strength. In this technical solution, the arc-shaped arrangement of the transverse stiffener 9 can effectively conform to the airflow direction, forming a continuous mechanical transmission path when the blade rotates, so that the centrifugal force is evenly distributed to the hub 1 connection area along the arc of the stiffener. The radial arc-shaped arrangement of the longitudinal stiffener 10 matches the blade bending deformation mode, and the bending stiffness can be significantly improved by optimizing the curvature distribution. The grid structure formed by the intersection of two types of arc-shaped reinforcing ribs constitutes a three-dimensional force flow network in space. Among them, the transverse rib 9 mainly bears the circumferential stress, while the longitudinal rib 10 mainly resists the radial bending moment. The synergistic effect of the two increases the overall structural stiffness by 15%-20%. Compared with the layout of straight reinforcing ribs, the arc design avoids stress concentration. Under the same material usage conditions, the maximum local stress can be reduced by 25%-30%.

[0032] In a further preferred embodiment, the thickness difference of the blade body 3 from the inner edge to the outer edge in the radial direction is controlled to within 5%. This technical solution, through strict control of thickness difference, enables the blade to form an approximately uniform strength structure in the radial direction. Regarding stress distribution, when the thickness gradient rate is reduced to below 5%, finite element analysis shows that the maximum stress concentration factor can be reduced from 2.1 in the traditional design to below 1.3. In terms of molding processability, the thickness uniformity reduces the temperature difference at the melt flow front to within 8°C, controls the volume shrinkage rate difference during the cooling stage to below 0.15%, and reduces the measured warpage deformation by 42% compared to the traditional structure.

[0033] Furthermore, this application proposes that the thickness of the reinforcing rib be 1 / 3 to 1 / 2 of the wall thickness of the hollow two-half structure. Specific methods for achieving the reinforcing rib thickness include, but are not limited to: using a straight rib structure with a uniform cross-section, the thickness of which remains consistent along the length of the rib; or using a variable thickness design, locally thickening to 1 / 2 of the wall thickness in stress concentration areas and thinning to 1 / 3 in non-critical areas; or using a stepped transition, setting a thickness gradient zone at the connection between the rib and the wall to avoid abrupt stress changes. The thickness of the reinforcing rib can be precisely controlled by the cavity dimensions of the injection mold, and verified by an ultrasonic thickness gauge after molding. This technical solution solves the problem of insufficient structural strength or material waste caused by unreasonable design of the reinforcing rib thickness inside the hollow two-half structure by limiting the proportional relationship between the reinforcing rib and the structural wall thickness. When the reinforcing rib thickness is less than 1 / 3 of the wall thickness, it is difficult to effectively transfer the load, leading to an increased risk of local buckling. When it exceeds 1 / 2 of the wall thickness, the increased melt flow resistance easily leads to incomplete filling defects. Experimental data shows that...

[0034] A ratio of 1 / 3 to 1 / 2 allows the stiffener's moment of inertia to reach its optimal value, ensuring bending stiffness while avoiding uneven cooling shrinkage caused by excessive stiffener thickness. Compared to existing technologies, this design shortens the injection molding cycle by 8%-12%, and fatigue tests have verified that it increases structural life by approximately 30% under the same load conditions.

[0035] Furthermore, the hub 1 and the blade body 3 are made of high-strength engineering plastics and are integrally molded using injection molding. High-strength engineering plastics can be selected from materials such as glass fiber reinforced polyamide (PA-GF), polybutylene terephthalate (PBT), or polyphenylene sulfide (PPS), with the glass fiber content controlled within the range of 15%-30%. During injection molding, a mold temperature controller is used to control the mold temperature at 80-120℃, the injection pressure is set at 80-120MPa, the holding pressure is 60%-80% of the injection pressure, and the holding time is calculated at 1-1.5s / mm based on the wall thickness. As a preferred embodiment, gas-assisted injection molding can be used, injecting 0.5-0.8MPa of nitrogen gas into the melt core during the holding pressure stage to reduce shrinkage stress. Specifically, the combination of high-strength engineering plastics and integral molding technology ensures that the high mechanical strength of the materials meets the centrifugal load requirements during high-speed rotation of the fan blades, with a tensile strength of at least 120MPa and a flexural modulus of not less than 5GPa. The one-piece molding process eliminates stress concentration points caused by traditional welding or bolted connections, increasing the fatigue strength of the connection area between hub 1 and blade 2 by more than 40%. During injection molding, precise control of the melt flow path and cooling rate allows for shrinkage control within the range of 0.3%-0.5%, ensuring that the blade profile accuracy error is less than 0.2mm. Compared to the solid thick-walled structure described in the background art, this solution effectively avoids porosity defects and warping deformation caused by uneven wall thickness while maintaining the same structural strength.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1.A plastic axial flow fan blade for air conditioner, comprising a hub (1) and a plurality of blades (2), the inner edges of the blades (2) are integrally connected to the outer wall surface of the hub (1) and arranged regularly in the circumferential direction; characterized in that: the blade (2) comprises a blade body (3) integrally formed with the hub (1), and a movable blade (4) buckled to the blade body (3) ; a groove (5) is formed on the leeward surface of the blade body (3), the movable blade (4) is buckled and fixed to the groove (5), and the edge of the movable blade (4) is connected to the edge of the groove (5) of the blade body (3) ; the blade body (3) and the movable blade (4) jointly form a hollow two-half structure, and the inside of the hollow two-half structure is provided with longitudinal and transverse intersecting reinforcing ribs. 2.The plastic axial flow fan blade for air conditioner according to claim 1, characterized in that: the buckle structure comprises elastic hooks (7) provided on the movable blade (4) and a clamping groove provided on the edge of the groove (5), and the elastic hooks (7) are locked by being embedded in the clamping groove through deformation. 3.The plastic axial flow fan blade for air conditioner according to claim 1, characterized in that: the groove (5) is located on the leeward surface of the blade near the leading edge of the blade, and the width of the groove (5) along the direction from the leading edge to the trailing edge of the blade accounts for 60% to 90% of the total width of the blade. 4.The plastic axial flow fan blade for air conditioner according to claim 2, characterized in that: the groove (5) is provided with reinforcing ribs, and when the movable blade (4) is buckled and fixed to the groove (5), the reinforcing ribs support the inner end surface of the movable blade (4). 5.The plastic axial flow fan blade for air conditioner according to claim 4, characterized in that: the reinforcing ribs comprise transverse reinforcing ribs (9) and longitudinal reinforcing ribs (10), the transverse reinforcing ribs (9) and the longitudinal reinforcing ribs (10) intersect to form a grid structure, and a grid cavity (11) is formed between adjacent reinforcing ribs. 6.The plastic axial flow fan blade for air conditioner according to claim 5, characterized in that: the transverse reinforcing ribs (9) are in an arc structure extending from the leading edge to the trailing edge of the blade, and the longitudinal reinforcing ribs (10) are in an arc structure extending from the inner edge to the outer edge of the blade. 7.The plastic axial flow fan blade for air conditioner according to claim 1, characterized in that: the thickness difference of the blade body (3) in the radial direction from the inner edge to the outer edge of the blade is controlled within 5%. 8.The plastic axial flow fan blade for air conditioner according to any one of claims 1 to 7, characterized in that: the thickness of the reinforcing ribs is 1 / 3 to 1 / 2 of the wall thickness of the hollow two-half structure. 9.The plastic axial flow fan blade for air conditioner according to claim 1, characterized in that: the materials of the hub (1) and the blade body (3) are high-strength engineering plastics, and the hub (1) and the blade body (3) are integrally formed by injection molding process. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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